This invention concerns the use of Vitamin D and its analogs in the treatment of tumors and hyperproliferative disorders.
Vitamin D is a generic term for a family of secosteroids that have affinity for the Vitamin D receptor, and are involved in the physiologic regulation of calcium and phosphate metabolism. Exposure to the sun and dietary intake are common sources of Vitamin D, but deficiencies of this vitamin can cause rickets and osteomalacia. Supplementation of dairy and other food products has reduced the incidence of Vitamin D deficiency conditions in modern society, and medical research concerning this vitamin has turned to its therapeutic effects in a variety of pathological conditions.
Vitamin D3 is synthesized in human skin from 7-dehydrocholesterol and ultraviolet light. Vitamin D3, or its analog Vitamin D2, can be ingested from the diet, for example in fortified milk products. Vitamin D2 and D3 undergo hydroxylation first in the liver to 25-hydroxyvitamin D, then in the kidney to 1xcex1,25-dihydroxycholecalciferol (also known as 1,25-dihydroxyvitamin D or calcitriol), which is the principal biologically active form of Vitamin D. The biological production of this active form of the vitamin is tightly physiologically regulated.
Vitamin D exerts its calcium regulating activity through both genomic and nongenomic pathways. Although the nongenomic pathways remain poorly characterized, the genomic responses are mediated through binding to the nuclear Vitamin D receptor (VDR). The VDR is a ligand-activated transcription factor, which binds the Vitamin D3 response element contained within the promoter/enhancer region of target genes. Vitamin D maintains calcium levels in the normal range by stimulating intestinal calcium absorption. When intestinal absorption is unable to maintain calcium homeostasis, Vitamin D stimulates monocytic cells to become mature osteoclasts, which in turn mobilize calcium from bones.
Appreciation for Vitamin D""s non calcium-related biological activities began in 1979, with Stumpf""s discovery that radioactive Vitamin D localizes to many tissues not associated with calcium metabolism (Science 206:1188-1190, 1979). In 1981, Abe et al. reported that mouse myeloid leukemia cells possessed VDR, and that their exposure to Vitamin D led to terminal differentiation (PNAS USA 78:4990-4994, 1981). Since then VDR has been described in carcinomas of the prostate, breast, colon, lung, pancreas, endometrium, bladder, cervix, ovaries, squamous cell carcinoma, renal cell carcinoma, myeloid and lymphocytic leukemia, medullary thyroid carcinoma, melanoma, multiple myeloma, retinoblastoma, and sarcomas of the soft tissues and bone.
In vitro assays using 1,25 dihydroxyvitamin D or its analogues demonstrated antiproliferative effects in cell lines derived from many malignancies including adenocarcinomas of the prostate (Molec. and Cell. Endocrinology 126:83-90, 1997; Proc. Amer. Assoc. Cancer Res. 38:456, 1997; J. Ster. Biochem. and Molec. Biol. 58:277-288, 1996; Endocrinology 137:1551561, 1996; Endocrinology 136:20-26, 1995; Cancer Research 54:805-810, 1994; Endocrinology 132:1952-1960, 1993; and Anticancer Research 14:1077-1081, 1994), breast (Proc. Amer. Assoc. Cancer Res. 38-456, 1997; Biochemical Pharmacology 44:693-702, 1992); colon (Biochemical and Biophysical Research Communications 179:57-62, 1991; Archives of Pharmacology 347:105-110, 1993); pancreas (British Journal of Cancer 73:1341-1346, 1996); and endometrium (Journal of Obstetrics and Gynaecology Research 22:529-539, 1996); lung (Anticancer Research 16:2953-2659, 1996); myeloid leukemia (PNAS USA 78:4990-4994, 1981); melanoma (Endocrinology 108:1083-1086, 1981); and sarcomas of the soft tissues (Annals of Surgical Oncology 3:144-149, 1996) and bone (Journal of the Japanese Orthopaedic Association 69:181-190, 1995).
Studies in animals have shown antiproliferative activity of Vitamin D or its analogues in prostate cancer (Urology 46:365-369, 1994); breast cancer (J. NCl 89:212-218, 1997; Lancet 1:188-191, 1989); squamous cell carcinoma (Molecular and Cellular Differentiation 3:31-50, 1995); myeloid leukemia (Blood 74:82-93, 1989 and PNAS USA 80:201-204, 1983) and retinoblastoma (Archives of Opthalmology 106:541-543, 1988; Archives of Opthalmology 106:536-540, 1988). The mechanism of Vitamin D""s antiproliferative effects remains unknown, although it has been proposed that Vitamin D increases synthesis of TGF-xcex21 and TGF-xcex22, decreases the expression of epidermal growth factor receptors, leads to dephosphorylation of the retinoblastoma protein, induces cell cycle arrest in G1, perhaps by induction of the cyclin dependent kinase inhibitors p21(waf1) and p27(kip1), and induces the production of insulin-like growth factor binding protein.
The patent literature is replete with attempts to treat tumors with Vitamin D compounds. U.S. Pat. No. 4,391,802 disclosed treating leukemioid diseases with 1xcex1-hydroxy Vitamin D derivatives. The use of 1xcex1-hydroxy derivatives with a 17 side chain greater in length than the cholesterol or ergosterol side chains was disclosed in U.S. Pat. No. 4,717,721. Additional Vitamin D analogs are described in U.S. Pat. No. 4,851,401 (cyclopentano-Vitamin D analogs), U.S. Pat. No. 4,866,048, U.S. Pat. No. 5,145,846 (Vitamin D3 analogs with alkynyl, alkenyl, and alkanyl side chains), U.S. Pat. No. 5,120,722 (trihydroxycalciferol), U.S. Pat. No. 5,547,947 (fluoro-cholecalciferol compounds), U.S. Pat. No. 5,446,035 (methyl substituted Vitamin D), U.S. Pat. No. 5,411,949 (23-oxa-derivatives), U.S. Pat. No. 5,237,110 (19-Nor-Vitamin D compounds), U.S. Pat. No. 4,857,518 (hydroxylated 24-homo-Vitamin D derivatives). Additional Vitamin D analogs are shown in U.S. Pat. Nos. 4,804,502; 5,374,629; 5,403,940; 5,446,034; and 5,447,924.
Few attempts have been made to test Vitamin D""s antiproliferative effects in humans with cancer. Koeffler et al., Cancer Treatment Reports 69:1399-1407, 1985, gave 2 mcg of 1,25-dihydroxyvitamin D daily for 8 weeks or longer to 18 patients with myelodysplastic syndrome. Eight of 18 patients had minor and transient improvements in the peripheral blood counts, but by the end of the 12 week study no patient showed significant improvement and 4 patients experienced symptomatic hypercalcemia. Bower et al., Lancet 337:701-702, 1991, treated 19 patients with locally advanced or cutaneous metastatic breast cancer with topical calcipotriol, a Vitamin D analogue. Three of the 14 patients who completed 6 weeks of treatment showed a 50% reduction in the bidirectional diameter of the treated lesions and one other patient showed minimal response, however hypercalcemia was a complication of the treatment. Palmieri-Sevier et al., Am. J. Medical Sciences 306:309-312, 1993, reported a case of long term remission of parathyroid carcinoma which appeared to be induced and maintained by Vitamin D therapy. Rustin et al., Brit. J. Can. 74:1479-1481, 1996, performed a clinical trial with a continuous dose of calcitriol in patients with ovarian cancer, and again encountered hypercalcemia.
A phase II trial of oral 1,25-dihydroxyvitamin D (calcitriol) in hormone refractory prostate cancer was reported by Osborn et al., Urol. Oncol., 1:195-198, 1995. Fourteen patients were given a daily oral dose of 0.5-1.5 mcg calcitriol, but no significant response was demonstrated, and clinical deterioration was documented in most of the patients. Thirteen of the patients experienced hypercalcemia, which is the most common side effect of treatment with Vitamin D and its analogs. Concern that hypercalcemic effects of Vitamin D would preclude the achievement of therapeutic, anti-neoplastic serum levels has inhibited the study of the use of this vitamin in humans with cancer. It is an object of this invention to provide a method of treatment with Vitamin D drugs (such as calcitriol) that avoids such hypercalcemia, while permitting the use of this class of drugs in the treatment of tumors and other hyperproliferative diseases.
Vitamin D and its analogs can be administered in accordance with the present invention, for the treatment of neoplastic diseases, such as the types of tumors mentioned above, which are responsive to treatment with Vitamin D drugs. The method can also be used to treat hyperproliferative skin diseases, such as psoriasis, disorders of keratinization and keratosis, or disorders of sebaceous glands, such as acne or sebonheic dermatitis. The method includes administering to the subject a therapeutically effective pulsed dose of the Vitamin D drug in a sufficient amount to have a therapeutic effect, without inducing hypercalcemia, particularly symptomatic hypercalcemia, for example grade 3 or stage 4 hypercalcemia. This treatment is especially effective to allow the use of highly calcemic drugs (such as drugs having a calcemic index of 0.5 or more) which are often highly effective in the treatment of tumors and hyperproliferative diseases, but which have been avoided in the past because of their calcemic side effects. The dosing regimen of the present invention for the first time allows therapeutically effective antiproliferative (and particularly antineoplastic) amounts of these drugs to be given without inducing the dangerous side effect of life-threatening hypercalcemia, while surprisingly having a prolonged therapeutic specific anti-tumor or general antiproliferative effect.
In a first disclosed embodiment, the Vitamin D drug is administered to a subject having a neoplasm that expresses a Vitamin D receptor, and responds to treatment with a Vitamin D drug. Particular types of tumor that respond to such treatment include adenocarcinomas of the prostate, breast, colon, pancreas and endometrium, as well as small cell and non-small cell cancer of the lung (including squamous, adenocarcinoma and large cell types), squamous cell carcinoma of the head and neck, transitional cell cancer of the bladder, ovarian and cervical (e.g. squamous cell carcinoma) cancer, renal cell carcinoma, myeloid and lymphocytic leukemia, lymphoma, medullary thyroid carcinoma, melanoma, multiple myeloma, retinoblastoma, and sarcomas of the soft tissues and bone. In particular embodiments, the neoplasm is adenocarcinoma of the breast or prostate.
In yet other specific embodiments, the Vitamin D drug is one that would induce hypercalcemia (particularly symptomatic or life-threatening hypercalcemia) in a subject to which the drug is given at antiproliferative doses. The method would have particular application to drugs that are as calcemic as calcipotriol (calcemic index of about 0.005-0.01), 11xcex1-fluoromethyl-1xcex1,25-(OH)2-D3 (having a calcemic index of about 0.1), and drugs having a calcemic index greater than 0.5, for example greater than or equal to 1 (the calcemic index of calcitriol). Drugs with which the method is particularly useful are those drugs having a half-life no greater than about 1 day, for example no greater than about 6 hours, when the dose is given as a therapeutically effective dose. These half-lives are sufficiently short that they allow the blood level to return to non-calcemic levels for a sufficient period between doses so that full osteoclast activation does not occur. In particular embodiments, blood levels of calcium return to normal between doses. The Vitamin D drug is administered in an amount that raises a serum level of Vitamin D in the subject with a tumor to a supraphysiologic amount for a sufficient period of time to induce differentiation or regression of the tumor without causing symptomatic hypercalcemia.
For example, where the Vitamin D analog is calcitriol, it can be administered in a high pulse dose no more than once every three days, for example once a week. Although calcitriol has been used in the past to treat cancer, dosages of such regimens have been 0.5-1.5 mcg per day for prolonged periods of time, which has caused symptomatic hypercalcemia. In accordance with some embodiments of the present invention, calcitriol is orally administered in a dose of at least 0.12 mcg/kg per day (8.4 mcg in a 70 kg person) no more than once every 5 or 6 days, for example once a week. In certain examples, the drug is administered no more than once every three days, or no more than once per week. Even higher doses of calcitriol are possible using the pulsed dose regimen of the present invention, for example administering the calcitriol orally in a dose of at least about 0.48 mcg/kg per day, for example 1 mg/kg per day or higher, e.g. 2-3 mg/kg per day, no more than once per week. As the dosage of the calcitriol or other Vitamin D drug increases, the interval between doses can be increased (for example to as long as 7-10 days) to avoid symptomatic hypercalcemia. It has surprisingly been observed that pulsed increases in the blood level of Vitamin D are sufficient to have an anti-tumor or antiproliferative effect for a prolonged period of time (e.g. 10 days), so that the dosing regimen of the present invention can be followed while encountering a lowered risk of hypercalcemia.
The invention also includes a pharmaceutical composition comprising a Vitamin D drug in a pharmaceutical dosage form containing at least 5 micrograms (mcg) of calcitriol, for example 5-100 mcg. The dosage form may be an oral, intravenous, intramuscular, topical, subcutaneous, transdermal, sublingual, intranasal, intratumoral or other preparation, but in particular disclosed embodiments the pharmaceutical dosage form is an oral dosage form, such as a tablet or capsule.
The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description of several preferred embodiments.